The present invention pertains to a protective member (e.g. a washer-like member) alone, a rotatable cutting tool that uses the protective member, as well as a cutting tool assembly that uses the protective member. More particularly, the invention pertains to a non-rotatable protective member (e.g., a non-rotatable washer) alone, a rotatable cutting tool that uses the non-rotatable protective member, as well as a cutting tool assembly that uses the non-rotatable protective member wherein the cutting tool assembly includes a cutting tool and a holder for the cutting tool wherein the cutting tool carries the non-rotatable protective member that engages the holder so as to be non-rotatable.
One typical use of a rotatable cutting tool is in conjunction with a machine used to break up (or cut) a substrate such as earth strata (e.g., coal, the ground, asphalt pavement, asphaltic concrete, concrete or the like). In its very basic aspects, such a machine includes a driven member (e.g., a chain, a wheel or a drum), a holder either directly or indirectly mounted to the driven member, and a rotatable cutting tool rotatably held in the holder. It is the cutting tool that impinges the earth strata so as to break it into pieces and chunks upon impact.
As can be appreciated these rotatable cutting tools and the holders operate in a severe environment that causes wear on these components, as well as other possible failures due to the severity of the operating conditions. While it is inevitable that the cutting tools experience wear, the ability of the cutting tool to rotate about its central longitudinal axis during operation generally prolongs the useful life of the cutting tool. It can thus be appreciated that features of the cutting tool or cutting tool assembly that facilitate the rotation of the cutting tool during operation are beneficial to the operation of the cutting tool (and cutting too assembly) and the overall operation of the earth strata cutting machine.
As known to those skilled in the art, the useful life of the holder is much longer than the useful life of the cutting tool. Each holder is intended to accommodate many changes of cutting tools held thereby until it is necessary to replace the holder. In the case of an earth strata cutting machine like a road milling machine, it is important to maintain the milling pattern. One factor that influences the milling pattern is the degree of wear that is suffered by the forward face of the holder. In order to reduce the wear on the forward face of the holder a washer has been carried by the cutting tool that is mediate of the cutting tool and holder. The washer protects the forward face of the holder from wear.
One such cutting tool that carries a protective washer is shown and described in U.S. Pat. No. 6,478,383 to Ojanen et al. The cutting tool of this patent carries a washer. When the cutting tool is received within the bore of a block, which is attached to a driven member, the washer is sandwiched between the rearwardly facing surface of the enlarged diameter portion of the cutting tool and the forward face of the holder.
Another cutting tool that uses a protective member is shown and described in U.S. Pat. No. 6,508,516 B1 to Kammerer. The '516 patent discloses a washer that includes a tab. The tab engages grooves in a holder so that the washer does not rotate relative to the holder.
While at least at the beginning of a milling cycle, the structure disclosed in U.S. Pat. No. 6,508,516 would be expected to provide a non-rotatable washer; however, over time the structure may be susceptible to problems. One such problem is that the groove that engages the tab may become clogged with debris. Obviously, this condition could compromise the integrity of the connection between the tab and the groove and result in the loss of the non- rotatable feature of the washer. Another problem is that over the course of operation the tab is exposed along the side of the tool so as to be susceptible to wearing away. The erosion of the tab could compromise the integrity of the connection between the tab and the groove and result in the loss of the non-rotatable feature of the washer.
U.S. Pat. No. 5,931,542 to Britzke et al. discloses a cutting tool that includes a protective member (i.e., a washer). The washer interconnects to the resilient retainer carried by the cutting tool. The connection between the washer and the retainer sleeve keeps the washer from rotating relative to the holder. The location of the connection between the washer and the sleeve is close to the longitudinal axis of the tool so that higher forces are applied to this connection than if the connection were more radially outward.
While the above patents show washers that do not rotate relative to the holder, it would still be desirable to provide an improved cutting tool (as well as a) cutting tool assembly that uses a non-rotatable protective member such as a washer.
It would be desirable to provide an improved cutting tool (as well as a cutting tool assembly) that uses a non-rotatable washer (i.e., non-rotatable protective member) that directly engages the holder that holds the cutting tool in such a fashion so that the washer is not susceptible to wear that compromises the integrity of the non-rotatable characteristic of the washer. In this regard, it would be especially desirable to provide such a non-rotatable washer that engages a commercially existing holder (e.g., the holder shown in U.S. Pat. No. 6,244,665 to Bise et al.) that does not require any structural modifications to receive the non-rotatable washer. It would be a further advantage if the non- rotatable washer did not compromise the integrity of the desirable features of the holder, such as, for example in the case of U.S. Pat. No. 6,244,665, the ability of the access grooves to assist in the removal of the cutting tool.
It would also be desirable to provide an improved cutting tool (as well as a cutting tool assembly) that uses a non-rotatable washer wherein the connection that provides the non-rotatable feature is protected from erosion or wear during operation.
It would also be desirable to provide an improved cutting tool (as well as a cutting tool assembly) that uses a non-rotatable washer (a non-rotatable protective member) that has a high torque strength for the connection that provides for the non-rotatable feature of the washer.
It would also be desirable to provide an improved cutting tool (as well as a cutting tool assembly) that uses a non-rotatable washer (i.e., a non-rotatable protective member) that can be used in conjunction with a rotatable washer.
It would also be desirable to provide an improved cutting tool (as well as a cutting tool assembly) that uses a pair of the non-rotatable washers.